Tub for humidifier

ABSTRACT

A humidifier includes a tub configured to hold a supply of water. The tub includes a tub lid and a tub base adapted to be coupled to the tub lid. The tub further includes a base plate formed of a heat conducting material and adapted to be coupled to the tub base and a seal positioned between the base plate and the tub base. The tub also includes a retaining mechanism with at least one projection that projects from the tub base and is configured to force the base plate against the seal so that the seal is secured against the tub base.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 12/134,310, filedJun. 6, 2008, now allowed, which claims priority to U.S. ApplicationNos. 60/942,567, filed Jun. 7, 2007, and 61/039,514, filed Mar. 26,2008, each of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a tub for a humidifier. The presentinvention also relates to a humidifier for a breathable gas supplyapparatus, and particularly but not exclusively, to such apparatus foruse in Continuous Positive Airway Pressure (CPAP) treatment ofconditions such as Obstructive Sleep Apnea (OSA) and other respiratorydisorders and diseases such as emphysema. Although the present inventionis described herein in its application to CPAP treatment apparatus, itshould be appreciated that the features of the present invention willhave application to other fields of application, such as a mechanicalventilation and assisted respiration.

BACKGROUND OF THE INVENTION

CPAP treatment of OSA, a form of Noninvasive Positive PressureVentilation (NIPPV), involves the delivery of a pressurized breathablegas, usually air, to a patient's airways using a conduit and a patientinterface, for example, a mask. Gas pressure employed for a CPAPtypically range from 4 cm H₂O to 28 cm H₂O, at flow rates of up to 180L/min (measured at the patient interface), depending on patientrequirements. The pressurized gas acts as a pneumatic splint for thepatient's airway, preventing airway collapse, especially during theinspiratory phase of respiration.

CPAP machines including an airflow generator for supplying pressurizedair to the patient are known, and over recent years there has beencommercial incentive for more compact CPAP machines. However, in seekingto reduce the size of the CPAP machines there has been a trade-offbetween reduced size on the one hand and reduced performance on theother.

The advantages of incorporating humidification of the air supply to apatient are known, and CPAP machines are known which incorporatehumidifying devices, either separately from the flow generator orintegrated therewith. An example of an integrated flowgenerator/humidifier is the ResMed S7 sold by the assignee of thepresent application. An example of a humidifier which is separatelyprovided to be connectable to a flow generator is disclosed in U.S.Patent Application Publication 2008/0072900 A1, the entire contents ofwhich are incorporated herein by reference.

It is known to provide a heating unit, such as a heating plate, to ahumidifier to increase the amount of water vapor in the flow ofbreathable gas. Reducing the size of CPAP machines, includinghumidifiers, has led to a decrease in the size of water containersmaking it more difficult to provide humidification of the air supplyduring the entirety of the patient's sleep cycle. The reduction in thesize of humidifier tubs results in a decrease in the surface area of thewater exposed to the flow of air provided by the flow generator. Thiscreates problems in maintaining a sufficient moisture pickup by theairflow passing through the tub and requires that the flow generatormotor run faster, which produces more noise. The integration ofhumidifiers with flow generators also makes it more difficult to cleanthe water container of the humidifier.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a humidifier tub that providesenhanced heating for use with a CPAP device.

Another aspect of the invention relates to a humidifier tub thatprovides increased usable water capacity for use with a CPAP device.

Still another aspect of the invention relates to a humidifier tub foruse with a CPAP device that includes a removable base plate to permitcleaning.

According to an embodiment of the invention, a humidifier comprises atub. The tub comprises a base plate; a tub base; a seal between the baseplate and the tub base; and a latch mechanism that connects the baseplate to the tub base so that the base plate is engaged with the seal.

According to another embodiment of the present invention, the humidifiercomprises a tub lid configured to cover the tub base. The tub and thetub lid form a water container.

According to still another embodiment of the present invention, thehumidifier comprises a cradle configured to receive the water container.

According to yet another embodiment of the invention, the cradle isconfigured to be connected to a flow generator that supplies an air flowto the water container.

According to a further embodiment of the invention, the cradle comprisesa hinged lid that is pivotable between an open position permittinginsertion of the water container into the cradle and a closed positioncovering the inserted water container.

According to an even further embodiment, the hinged lid comprises an airoutlet pipe configured to communicate with an outlet of the tub lid whenthe lid is the closed position.

According to another embodiment of the invention, the cradle comprises aheating element configured to contact the base plate when the watercontainer is inserted into the cradle.

According to another embodiment, a CPAP device includes a humidifieraccording to the invention.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 schematically illustrates a humidifier according to one sampleembodiment of the present invention;

FIG. 2 schematically illustrates a water container of the humidifier ofFIG. 1;

FIG. 3A schematically illustrates an exploded assembly view of thecleanable water container of FIG. 2;

FIG. 3B schematically illustrate a bottom perspective view of a variantof a base plate usable in the assembly of FIG. 3A;

FIG. 3C schematically illustrates a side elevation view of the cleanablewater container of the humidifier of FIG. 1;

FIG. 3D schematically illustrates a pivot hinge usable with the watercontainer of FIGS. 3A-3C;

FIG. 4 schematically illustrates a rear elevation view of the cleanablewater container of FIGS. 2 and 3A-3D;

FIGS. 5 and 6 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIG. 7 schematically illustrates a humidifier tub according to anothersample embodiment of the invention;

FIG. 8 schematically illustrates a humidifier tub according to anothersample embodiment of the present invention;

FIG. 9 schematically illustrates a humidifier tub according to anothersample embodiment of the present invention;

FIG. 10 schematically illustrates a humidifier tub according to anothersample embodiment of the present invention;

FIGS. 11 and 12 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention and FIG. 12Aillustrates an additional variant;

FIGS. 13 and 14 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIGS. 15 and 16 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIG. 17 schematically illustrates a humidifier tub according to anothersample embodiment of the present invention;

FIGS. 18 and 19 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIGS. 20-23 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIGS. 24-26 schematically illustrate a humidifier tub according toanother sample embodiment of the present invention;

FIGS. 27-32 schematically illustrate a humidifier tub according toanother sample embodiment of the invention;

FIGS. 33 and 34 schematically illustrate a humidifier and humidifier tubaccording to another sample embodiment of the invention;

FIGS. 35 and 36 schematically illustrate a humidifier tub according toanother sample embodiment of the invention;

FIGS. 37 and 38 schematically illustrate a humidifier tub according toanother sample embodiment of the invention;

FIG. 39 schematically illustrates a humidifier and humidifier tubaccording to another sample embodiment of the invention; and

FIG. 40 schematically illustrates a humidifier according to anothersample embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodimentswhich may share common characteristics and features. It is to beunderstood that one or more features of any one embodiment may becombinable with one or more features of the other embodiments. Inaddition, any single feature or combination of features in any of theembodiments may constitute additional embodiments.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that the blowersdescribed herein may be designed to pump fluids other than air.

1.0 Humidifier

Referring to FIG. 1, a humidifier 10 according to an embodiment of thepresent invention includes a humidifier control base or cradle 12 and alid 14 hinged to the cradle 12. The hinged lid 14 includes an air outletpipe 16 which is configured for connection to a hose to deliver a supplyof pressurized, breathable gas to a patient via a patient interface,such as a mask. The humidifier 10 includes a water container 20 which isconfigured to store a supply of water used to humidify the supply ofbreathable gas. The water container 20 is configured to be inserted, or“dropped,” into the cradle 12. The hinged lid 14 is pivotable to an openposition (not shown) for insertion of the water container 20 andpivotable to the closed position shown in FIG. 1 to secure the watercontainer 20 in an operable position for connection of the humidifier 10to a flow generator (not shown). The cradle 12 facilitates the correctassembly of the humidifier 10 with a flow generator. The cradle 12 mayinclude a heating element or plate to heat water within the container20. Upon insertion of the water container 20 into the cradle 12, theheating element contacts a base plate of the water container 20.

When operating with a hose attached, the lid 14 may be snapped down tocreate an airtight path, for example using a seal or seals. When thehumidifier needs refilling, cleaning, and/or maintenance, the lid may beraised, with the hose still attached, so that the water container iseasily accessible. The seal, or seals, of the lid 14 also forms a partof a spill back protection and spitting requirements that protect boththe patient and a flow generator. The humidifier is designed to work ina hot and/or humid environment and may be formed of a material that isdurable and safe for the patient.

The humidifier is configured to be connected to a flow generator. Forexample, the humidifier may be connected to a flow generator in a mannersimilar to that disclosed in WO 2004/112873 A1, the entire contents ofwhich are incorporated by reference herein.

2.0 Tub First Embodiment

As shown in FIG. 2, the water container 20 includes a tub 22 and a tublid 24. The tub lid 24 includes an air inlet aperture 24 a thatcommunicates with an air outlet aperture of the flow generator when thehumidifier 10 is connected to the flow generator. The tub lid 24 alsoincludes a U-shaped air passage 24 b and a humidified air outlet 24 c.The humidified air outlet 24 c communicates with the air outlet pipe 16when the hinged lid 14 is in the position shown in FIG. 1 to deliverhumidified air to the delivery hose.

Referring to FIG. 3A, the tub 22 includes a base plate 26 and a tub base30. The base plate 26 may be formed by stamping, for example, astainless steel plate. A stamped ring 27 may be formed on the base plate26 to provide structural rigidity to the base plate 26 so as to providea flat surface 29. The base plate 26 is also formed with alignment tabs25 and latch tabs 21.

A face seal 28 is provided between the base plate 26 and the tub base30. The base plate 26 is attached to the tub base 30, with the face seal28 therebetween, by inserting the alignment tabs 25 into alignment slots31 formed in the tub base 30. The portion of the tub base 30 definingthe alignment slots 31 may act as feet for the tub 22 to keep the tub 20level when filling. The alignment slots 31 may be spaced, for example,about 5 mm-15 mm apart, for example about 10 mm. The alignment slots 31are asymmetrical to ensure correct placement of the base plate 26.

An overcenter latch 38 is connected to the tub base 30 by pivot hinges36 (FIG. 3D) and the tub 22 is sealed by pivoting the overcenter latch38 so that latches 39 catch to engage the latch tabs 21 of the baseplate 26 to provide a substantially waterproof sealed connection betweenthe tube base 30 and the base plate 26. The latches 39 catch to engagethe latch tabs 21 when the overcenter latch 38 is in the engagedposition (see FIG. 4) to bias the base plate 26 towards the tub base 30.The face seal 28 is compressed between the base plate 26 and the tubbase 30 by the overcenter latch 38 to provide the substantiallywaterproof seal. As shown in FIG. 4, the overcenter latch 38 may includea textured surface 37 to improve a user's grip on the overcenter latch38 to permit the overcenter latch 38 to be moved between the engaged anddisengaged positions.

The tub base 30 includes a bottom peripheral edge 34 which includes arim 35 that defines an opening 32 in the tub base 30. The face seal 28has a shape generally corresponding to the bottom peripheral edge 34 ofthe tub base 30 and the face seal 28 has a width that is sufficient topermit some misalignment between the tub base 30 and the base plate 26while still maintaining the substantially waterproof seal. The bottomperipheral edge 34 serves to conceal the edges of the base plate 26,loosely retain the seal 28 during connection of the tub base 30 to thebase plate 26, and protect the seal 28 from the edges of the base plate26 during the connection.

When assembled, the connection of the latch catches 39 and the latchtabs 21 and the insertion of the alignment tabs 25 into the alignmentslots 31 define a generally triangular compression region for the faceseal 28, which may be, for example, an O-ring. As shown in FIG. 3A, theseal 28 may have a generally D-shaped configuration. It should beappreciated, however, that the seal 28 may have another shape, forexample an oval shape.

The base plate 26 may also comprise raised edges 23 between the latchtabs 21 and between the latch tabs 21 and the alignment tabs 25. Theraised edges 23 add stiffness to the base plate 26 to permit the baseplate 26 to resist bending under the stresses induced by the pressure ofcompressing the seal 28. The stamped ring 27 acts to isolate the contactsurface of the base plate 26 from the installation forces and enable theseal pressing process to maintain a flat region. In a variant shown inFIG. 3B, the stamped ring 27 may be formed to match the shape of theseal 28.

The tub base 30 may include one or more ribs 37 a provided around aportion of the perimeter of the opening 32 to stiffen the portion of thetub base 30 that will experience high connection forces. The rearportion of the tub base 30 will experience high connection forces whenthe overcenter latch 38 is connected to the latch tabs 21. The rearcorners of the tub base 30 will experience the highest connection forcesas the latch catches 39 are connected to the tub base 30 at theselocations. The rib 37 a act to prevent deflection of the rear portion ofthe tub base 30. A central gap 37 may be provided in the rib 37 a toenable water to drain onto the base plate 26 and ensure that all of thewater in the tub 22 is usable.

Referring to FIGS. 3C and 3D, the pivot hinges 36 are secured to the tubbase 30 by pivots 36 b of the pivot hinge 36. The rear of the tub base30 may include four protrusions having holes in each protrusion toaccept the pivots 36 b of the pivot hinges 36. The latch catches 39include holes or apertures 39 a (FIG. 3A) configured to receiverespective pivots 36 a of the pivot hinge 36.

The overcenter latch 38 forms a part of the user interface for thehumidifier tub. The overcenter latch 38 provides the interfaces foropening and closing the overcenter latch 38 and it interfaces with thebase plate 26 to produce the compression force on the face seal 28.

2.1 Tub Second Embodiment

Referring to FIGS. 5 and 6, according to another embodiment of thepresent invention, the tub base 30 a may include a plurality of lockingtabs 40 a-40 d. The base plate 26 a is inserted over the opening 32 a inthe tub base 30 a as shown by the arrows in FIG. 5. It should also beappreciated that the base plate 26 a may be inserted over the opening ina direction perpendicular to the direction shown by the arrows. Thelocking tabs 40 a-40 d are resilient and are received in locking slots42 a-42 d provided in the base plate 26 a in a snap-in manner. A groove44 surrounds the periphery of the opening 32 a in the tub base forreceipt of a seal 46, such as an O-ring. The tub base 30 a may alsoinclude fastener fittings 41 for receipt of fasteners 48. It should beappreciated that the fasteners 48 may be any releasable fastener.

2.2 Tub Third Embodiment

Referring to FIG. 7, the base plate 26 b may be releasably secured tothe tub base 30 b by tabs 33 formed on the tub base 30 b and snap rings50. The base plate 26 b is placed over the opening 32 b in the tub base30 b in contact with the seal 46 b. The snap rings 50 are then placedover the base plate 26 b and in engagement with the tabs 33 to securethe base plate 26 b between the snap rings 50 and the seal 46 b. Thetabs 33 are resiliently deformed by insertion of the snap rings 50 sothat the snap rings 50 are secured in the position shown in FIG. 7.

2.3 Tub Fourth Embodiment

According to another embodiment shown in FIG. 8, the base plate 26 c maybe secured to the tub base 30 c by tabs 33 c and a seal 46 c. The seal46 c may be secured to the tub base 30 c so as to secure the base plate26 c between the seal 46 c and the tabs 33 c.

2.4 Tub Fifth Embodiment

According to another embodiment shown in FIG. 9, the base plate 26 d maybe secured to the tub base 30 d by tabs 33 d. A groove 44 d is providedin the tub base 30 d and the seal (e.g., O-ring) 46 d is provided in thegroove 44 d to seal the connection between the base plate 26 d and thetub base 30 d.

2.5 Tub Sixth Embodiment

Referring to FIG. 10, the tub base 30 e includes a groove 44 e toaccommodate a seal 46 e, such as an O-ring. Alignment tabs 25 e of thebase plate 26 e are inserted into alignment slots 31 e in the tub base30 e and the opposite end of the base plate 26 e is then pivoted towardthe tub base 30 e. An overcenter latch 38 e connected to the tub base 30e by a pivot hinge 36 e. After the alignment tabs 25 e of the base plate26 e are inserted into the alignment slots 31 e, the opposite end of thebase plate 26 e is pivoted toward the tub base 30 e. A first end of theovercenter latch 38 e is pivoted into engagement with opposite end ofthe base plate 26 e and the second end of the overcenter latch 38 e isthen pivoted into the assembled condition such that a pin 70 of thepivot hinge 36 e is placed in a notch 72 in the tub base 30 e.

2.6 Tub Seventh Embodiment

Referring to FIGS. 11 and 12, the tub base 30 f includes a groove 44 ffor accommodating a seal 46 f. Tabs 52 are provided on the tub base 30 fand the base plate 26 f is assembled to the tub base 30 f by insertingthe base plate 26 f to the tube base 30 f in the direction shown by thearrows in FIG. 11. The tabs 52 are resilient and the base plate 26 fcauses an elastic displacement of the tabs 52 upon insertion. Thedisplaced tabs 52 remain somewhat displaced upon full insertion of thebase plate 26 f to bias the base plate 26 f in contact with the seal 46f. Referring to FIG. 12 a, the tabs 52 may include tamper evidentprojections. The tamper evident projections provide evidence oftampering with the base plate 26 f in a situation in which the baseplate 26 f is designed to be removed only by technician. The tabs have aslot 96 with a fragile rib 98 which would crush if tampered with.

2.7 Tub Eighth Embodiment

According to another embodiment of the present invention shown in FIGS.13 and 14, alignment tabs 25 g of the base plate 26 g are inserted intoalignment slots 31 g in the tub base 30 g. The opposite end of the baseplate 26 g is then pivoted toward the tub base 30 g in the directionshown by the arrow in FIG. 13. The base plate 26 g is pivoted intoconnection with a seal 46 g which is accommodated in a recess 44 g inthe tub base 30 g. Resilient tabs 52 g are provided for securing thebase plate 26 g to the tub base 30 g. The tabs 52 g include texturedfinger grips 54.

2.8 Tub Ninth Embodiment

Referring to FIGS. 15 and 16, according to another embodiment of thepresent invention, the base plate 26 h is attached to the tub base 30 hin the direction shown by the arrow 1A then 2A in FIG. 16. Lips 56 onthe tub base 30 h receive the inserted end of the base plate 26 h. Asshown in FIG. 16, the base plate 26 h is then pivoted into engagementwith a seal 46 h accommodated in groove 44 h of the tub base 30 h. Thebase plate 26 h includes an inclined second end 58 which is pivoted pastresilient tabs 52 h which include finger grips 54 h. The second end 58of the base plate 26 h may include a textured surface 23 to improve theuser's grip on the base plate 26 h. As shown in FIG. 15, a depression 60is formed into the tub base 30 h to facilitate insertion of a user'sfinger upon initial displacement of the base plate 26 h to thedisassembled position and to permit easier removal of the base plate 26h from the tub base 30 h. The base plate 26 h may be removed in thedirection opposite to the arrow shown in FIG. 15.

2.9 Tub Tenth Embodiment

Referring to FIG. 17, a seal 62 is provided between the base plate 26 jand the tub base 30 j. The seal 62 acts as a spring to bias the baseplate 26 j. The seal 62 may be used in any of the embodiments disclosedherein.

2.10 Tub Eleventh Embodiment

Referring to FIGS. 18 and 19, a base unit 62 includes latches 64 arounda top perimeter to lock the tub base 30 k into engagement with the seal28 k. The base plate 26 k is provided between the base unit 62 and thetub base 30 k and the seal 28 k is sandwiched between the base plate 26k and the tub base 30 k. As shown in FIG. 19, the latches 64 secure thecontact between the tub base 30 k and the seal 28 k and the contactbetween the seal 28 k and the base plate 26 k to form a substantiallywaterproof seal. The base unit 62 includes an opening 63. A heatingelement or unit 80, such as a ceramic plate, is received in the opening63 so as to be in contact with the base plate 26 k when the tub isassembled in the base unit 62. Contact between the base plate 26 k andthe heating element 80 is maintained by the engagement of the latches 64with the tub base 30 k. The latches 64 bias the tub base 30 k toward thebase plate 26 k thus biasing the base plate 26 k into contact with theheating element 80. The base unit 62 may be provided as an integral partof the casing 12, or separate from the casing.

2.11 Tub Twelfth Embodiment

According to another embodiment of the present invention shown in FIGS.20-23, a first end of the base plate 26 m is inserted into the tub base30 m and held in place by lips 56 m. The second, opposite end of thebase plate 26 m is secured by overcenter cams 68 that engage cam levers66 provided on the base plate 26 m. Each overcenter cam 68 is pivotablyattached to the tub base 30 m so as to be received in a recess 72 intothe tub base 30 m. Each overcenter cam 68 includes a linkage 70 whichengages the cam lever 66 of the base plate 26 m to secure the attachmentof the base plate 26 m to the tub base 30 m. A surface texture 78, suchas depressions or projections, may be provided to the overcenter cams 68that improve a user's grip on the overcenter cams 68.

2.12 Tub Thirteenth Embodiment

Referring to FIGS. 24-26, another sample embodiment of the humidifiertub 122 may comprise a tub base 130 and a base plate 126. A seal 128(FIG. 26) is compressed between a bottom peripheral edge 135 of the tubbase 130 and the base plate 126 to form a water tight tub 122. The baseplate 126 may comprise a stamped ring 127, which may have a shapecorresponding to the seal 128.

The base plate 126 may be permanently attached to the tub base 130 bytabs, or snaps, 138 formed in the tub base 130 that engage latch tabs121 on the base plate 126. The tabs, or snaps, 138 may be similar to thetabs shown, for example, in FIGS. 11-16. The snaps 138 are arranged insets of two, symmetrical around the center of the tub base 130, andtogether with alignment tabs 125 of the base plate 126 that are insertedinto alignment slots (not shown) of the tub base 130, form a generallytriangular compression region for the seal 128.

The snaps 138 grip opposite sides of the latch tabs 121 on the baseplate 126 and provide the force for compressing the seal 128 and holdthe base plate 126 in position for heat staking As shown in FIGS. 24-26,the base plate 126 comprises apertures 129 in the latch tabs 121. Thetub base 130 further includes heat stakes 134 that extend through theapertures 129 in the latch tabs 121, as shown in FIG. 26. The heatstakes 134 are passed through apertures in the seal 128 and through theapertures 129 in the base plate 126. The top of the heat stake is thenmelted, for example using a heated probe or an ultrasonic horn, tocreate a blob of plastic. The dome 134 a of the heat stake 134 assistsin holding the base plate 126 in position in a permanent manner that isclearly visible.

2.13 Tub Fourteenth Embodiment

Referring to FIGS. 27-32, a humidifier tub 222 according to anothersample embodiment comprises a tub base 230 and a base plate 226. Thebase plate 226 may be formed, for example, as a generally oval stainlesssteel plate pressed from coil. The base plate 226 comprises a rib 225that isolates a contact surface 227 from forces that connect the baseplate 226 and the tub base 230 and maintain a flat surface 229 of thebase plate. A seal 228 is provided on the contact surface 227.

The base plate 226 is connected to the tub base 230 by a snap ring 250.The snap ring 250 includes a contact surface 252. When the tub isassembled, the contact surface 252 engages the bottom of the seal 228and the top of the seal 228 is engaged by the contact surface 227 of thebase plate 226. The seal 228 is compressed between the contact surface252 of the snap ring 250 and the contact surface 227 of the base plate226.

As shown in FIGS. 28-30, the snap ring 250 is connected to the tub base230, with the base plate 226 in between, by the engagement of snaps 254formed on the inner periphery of the snap ring 250 that engage snaps 234formed around the periphery of an opening 232 in the tub base 230. Theperiphery of the opening 232 of the tub base 230 also includes aplurality of alignment or guide tabs 235 that are received in a channel255 in the periphery of the snap ring 250. The alignment or guide tabs235 are received between the snaps 254 of the snap ring 250 when thesnap ring 250 is connected to the tub base 230. The alignment or guidetabs 235 thus prevent the snap rings 250 from rotating relative to thetub base 230 and disengagement of the snaps 234, 254.

As shown in FIG. 29, the alignment or guide tabs 235 are providedbetween the snaps 234 around the periphery of the opening 232. Althougheight snaps 234, 254 are shown on the tub base 230 and snap ring 250,respectively, it should be appreciated that any number of snaps may beprovided. It should also be appreciated that the opening 232, the snapring 250 and the base plate 226 may have a shape other than oval, forexample circular.

The snap ring 250 retains the base plate 226 to the tub base 230 andprevents the removal of the base plate 226 from the tub base 230. Thecontact surfaces 252, 227 put pressure on the seal 228 and compress theseal 228 between the snap ring 250 and the base plate 226.

The seal 228 may be a face oriented O-ring. A face oriented O-ring maybe used, as the seal is not relied on to retain the base plate 226,which eliminates the effect of friction on the installation of the baseplate 226 and retention of the base plate 226. The face oriented O-ring228 has a shape generally corresponding to the contact surfaces 227, 252and has a width that is sufficient to permit some misalignment betweenthe tub base 230 and the base plate 226 while still maintaining thesubstantially waterproof seal. This provides a more reliable and robustseal.

The tub base 230, the base plate 226 and the snap ring 250 are designedto be assembled along a single axis and in one plane. This enables thetub 222 assembly process to be automated, which reduces the cost ofmanufacture and part-to-part variation.

2.14 Tub Fifteenth Embodiment

Referring to FIGS. 33 and 34, a humidifier 10 according to anothersample embodiment comprises a lid 14 having an outlet 16 configured forconnection to a hose or conduit. A tub of the humidifier comprises atube base 330, a base plate 326 and a seal 328 provided between the tubbase 330 and the base plate 326. The base plate 326 comprises aperipheral, e.g. annular, wall 352 that may be folded as shown in FIG.34 to compress the seal 328 between the base plate 326 and a bottom edge334 of the tub base 330. The peripheral wall 352 may be folded, forexample, by bending the peripheral wall 352, to compress the seal 328between the bottom edge 334 and the base plate 326. The base plate 326may be made, for example, for metal, such as stainless steel.

2.15 Tub Sixteenth Embodiment

Referring to FIGS. 35 and 36, the base plate 426 of the humidifier tubmay comprise an annular wall 451 that includes a curved, or hooked, end452 that is configured to engage the bottom peripheral edge 434 of thetub base 430. The bottom peripheral edge 434 may include a groove, orchannel, 435 configured to accommodate a seal 428, e.g. an O-ring, thatis compressed between the base plate 426 and the tub base 430 when thecurved end 452 of the base plate 426 engages the bottom peripheral edge434 of the tub base 430.

2.16 Tub Seventeenth Embodiment

Referring to FIGS. 37 and 38, the base plate 526 of the humidifier tubmay comprise an annular wall 551 having a plurality of resilient tabs552 formed therein. The resilient tabs 552 are configured to engage thebottom peripheral edge 534 of the tub base 530 to compress a seal 528,e.g. an O-ring, between the base plate 526 and the tub base 530. Thebottom peripheral edge 534 of the tub base 530 may comprise a groove, orchannel, 535 to accommodate the seal 528.

2.17 Tub Eighteenth Embodiment

Referring to FIGS. 39 and 40, a humidifier 10 may comprise a lid 14having an outlet 16 configured for connection to a hose or conduit. Thehumidifier may also comprise a water container comprising a tubincluding a tub lid 24 and a tub. The tub comprises a tube base 630 anda base plate 626. The tub base 630 may comprise an opening 632surrounded by a bottom peripheral edge 634. The base plate 626 isconfigured to cover the opening 632 and a seal 628 is provided to sealthe connection of the base plate 626 to the tub base 630. The tub basecomprises heat stakes 635 that are received in apertures 626 a, 628 a inthe base plate 626 and seal 628, respectively. The ends of the heatstakes 635 are melted, for example by a heated probe or ultrasonically,to form a dome portion similar to the manner described above topermanently connect the base plate 626 to the tube base 630.

As shown in FIG. 40, a cross beam channel 700 is configured forinsertion into an inlet 24 a of the tub lid 24. The cross beam channelincludes flexible tabs that permit insertion of the cross beam channel700 into the inlet 24 a, but prevent removal of the cross beam channel700 after insertion. The cross beam channel also comprises a curved end702. The curved end 702 has the dual function of guiding the inlet airover the surface of the water, and to provide spill back protection.

The base plate of the embodiments of the present invention may be formedof a material that provides good heat conduction, for example metal. Thebase plate may be formed, for example, of stainless steel. As discussedabove, the base plate is configured to be in contact with a heatingdevice, such as a ceramic heating pad or plate, to increase the amountof water vapor in the supplied air. A stainless steel base platetransfers more heat to the water in the tub. Increasing the heattransfer from the base plate to the water in the container by using astainless steel plate also reduces the energy consumption of thehumidifier. Transferring more heat to the water in the tub also allowsfor an increase in the capacity of the tub while maintaining therequired level of humidification.

The use of a stamped stainless plate for the base plate also reduces thecost of the humidifier as it is less expensive to provide a stampedplate than a machined plate. To further reduce costs, the tub base maybe formed of a plastic material. The tub according to the presentinvention may also be removed from the humidifier and easily cleaned,for example by placing the tub in a dishwasher.

Although the embodiments described above include seals that are separatefrom the tub base and the base plate, it should be appreciated that theseal may be formed so as to be integral with the tub base or the baseplate, for example by overmolding the seal with the tub base.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of any given assembly may constitute an additional embodiment.Furthermore, each individual component of any given assembly, one ormore portions of an individual component of any given assembly, andvarious combinations of components from one or more embodiments mayinclude one or more ornamental design features. In addition, while theinvention has particular application to patients who suffer from OSA, itis to be appreciated that patients who suffer from other illnesses(e.g., congestive heart failure, diabetes, morbid obesity, stroke,barriatric surgery, etc.) can derive benefit from the above teachings.Moreover, the above teachings have applicability with patients andnon-patients alike in non-medical applications.

What is claimed is:
 1. A humidifier adapted to be connected to a flowgenerator, the humidifier comprising: a humidifier cradle having abottom surface with a heating element and a side face configured toengage the flow generator and facilitate attachment of the humidifier tothe flow generator; a humidifier lid hinged to the humidifier cradle,the humidifier lid including a seal and an air outlet pipe configured tobe connected to a hose to deliver a supply of pressurized, breathablegas to a patient via a patient interface; and a water containerconfigured to store a supply of water used to humidify the supply ofbreathable gas and configured to be received by the humidifier cradle,the water container comprising: a tub lid; and a tub adapted to becoupled to the lid, the tub comprising: a base plate with raised edges,a perimeter of the base plate including a plurality of tabs withapertures; a tub base with a bottom peripheral edge that includes a rimdefining an opening, the tub base including a plurality of tab receivingportions configured to receive the plurality of base plate tabs and aplurality of heat stakes that extend through the apertures in the baseplate tabs, each heat stake having a melted head portion that is largerthat a corresponding aperture; and a tub seal positioned between thebase plate and the tub base, the tub seal having a shape that generallycorresponds to the bottom peripheral edge of the tub base, wherein thehumidifier lid is pivotable to an open position that accomodatesinsertion of the water container into the humidifier cradle, andpivotable to a closed position that secures the water container in anoperable position in the humidifier cradle, wherein the heating elementis configured to contact the base plate of the tub when the watercontainer is inserted into the humidifier cradle, wherein the humidifierlid is configured to be raised with the hose still attached, wherein thehumidifier lid seal is configured to engage the tub lid when thehumidifier lid is in the closed position, and wherein the tub lid isconfigured to communicate with the air outlet pipe when the humidifierlid is in the closed position.
 2. A humidifier according to claim 1,wherein the melted head portions of the heat stakes assist in holdingthe base plate against the tub base.
 3. A humidifier according to claim2, wherein the melted head portions are in the shape of a dome.
 4. Ahumidifier according to claim 3, wherein the heat stakes compriseplastic.
 5. A humidifier according to claim 4, wherein the tub seal isan O-ring.
 6. A humidifier according to claim 5, wherein the tub seal iscompressed between the base plate and the bottom peripheral edge of thetub base.
 7. A humidifier according to claim 5, wherein the bottomperipheral edge of the tub base includes a channel configured toaccommodate the tub seal.
 8. A CPAP machine comprising: a flowgenerator; and the humidifier of claim
 1. 9. A tub for a humidifierconfigured to hold a supply of water, the tub comprising: a tub lid; atub base adapted to be coupled to the tub lid; a base plate formed of aheat conducting material and adapted to be coupled to the tub base; aseal positioned between the base plate and the tub base; and a retainingmechanism with at least one projection that projects from the tub baseand is configured to force the base plate against the seal so that theseal is secured against the tub base.
 10. A tub according to claim 9,wherein the at least one projection comprises a stake extending from thetub base through apertures in the base plate, the stakes beingconfigured to be melted to maintain the seal in compression between thetub base and the base plate.
 11. A tub according to claim 10, whereinthe base plate comprises a plurality of tabs configured to be receivedby a plurality of tab receiving portions in the tub base.
 12. A tubaccording to claim 11, wherein the apertures of the base plate areprovided in the tabs.
 13. A tub according to claim 12, wherein theapertures are provided in the tabs of the base plate.
 14. A tubaccording to claim 13, wherein the stakes include melted head portionsthat are larger than the apertures and are configured to assist inholding the base plate against the tub base.
 15. A tub according toclaim 14, wherein the melted head portions are in the shape of a dome.16. A tub according to claim 15, wherein the stakes comprise plastic.17. A tub according to claim 16, wherein the heat stakes are configuredto be heated ultrasonically or by a heated probe.
 18. A humidifiercomprising: the tub of claim 9; a humidifier cradle configured toreceive the tub; and a humidifier lid hinged to the humidifier cradle.19. A tub for a humidifier configured to hold a supply of water, the tubcomprising: a base plate with raised edges, a perimeter of the baseplate including a plurality of tabs with apertures; a tub base with abottom peripheral edge that includes a rim defining an opening, the tubbase including a plurality of tab receiving portions configured toreceive the plurality of base plate tabs and a plurality of stakes thatextend through the apertures in the base plate tabs, each heat stakehaving a melted head portion that is larger that a correspondingaperture; a seal positioned between the base plate and the tub base, theseal having a shape that generally corresponds to the bottom peripheraledge of the tub base; and a tub lid adapted to be coupled to the tubbase.
 20. A tub according to claim 19, wherein the melted head portionsof the stakes assist in holding the base plate against the tub base. 21.A tub according to claim 20, wherein the melted head portions are in theshape of a dome.
 22. A tub according to claim 21, wherein the stakescomprise plastic.
 23. A tub according to claim 22, wherein the seal isan O-ring.
 24. A tub according to claim 19, wherein tub seal iscompressed between the base plate and the bottom peripheral edge of thetub base.
 25. A tub according to claim 19, wherein the bottom peripheraledge of the tub base includes a channel configured to accommodate thetub seal.
 26. A humidifier comprising: the tub of claim 19; a humidifiercradle configured to receive the tub; and a humidifier lid hinged to thehumidifier cradle.